In the production of paper, a layer of fiber slurry is deposited upon a belt. The belt is permeable, and some of the liquid in the slurry is drawn by vacuum through the belt, leaving a damp fiber layer. This damp layer is transferred onto another belt made of papermaking felt, and this second belt, together with the damp fiber layer on it, passes through rollers which squeeze out some more liquid from the fiber layer. Subsequently, the fiber layer is dried to evaporate more of the liquid and leave a layer of dry paper. As the drying or evaporation process is expensive, it is important to remove as much liquid as possible before the evaporation step. To this end, many variations of rollers and papermaking felts have been tried.
It has been found in accordance with the invention described and claimed herein that papermaker's felts with improved capacities for liquid removal are possible when the felt is modified by a pattern of beads. This modified felt is the subject of copending application Ser. No. 723,967 filed Sept. 16, 1976, which is hereby incorporated by reference. This application describes and claims the apparatus of making such beaded papermaking felt.
Prior U.S. Pat. No. 3,549,712 discloses a method of making an apertured belt that, as described above, is to be drawn over a vacuum. U.S. Pat. Nos. 3,915,202; 3,928,699; 3,657,068; 3,617,442; 3,603,354 and 3,613,258 disclose various types of papermaking felt, but none of them discloses the paper-making felt to which said copending specification is directed or the apparatus for the making of such felt to which this specification is directed. U.S. Pat. No. 3,772,055 discloses a method for strengthening fabric by applying dots of stiffening agent. The stiffening agent is printed onto the fabric by screen stencils. There is also art in this field of a papermaking felt with lines or rows of plastic backing applied to its working surface.